a) Field of the Invention
The present invention relates generally to controlling apparatus and method for controlling a duty ratio for a cooling fan associated motor (hereinafter, also simply referred to as a fan motor) of an automotive vehicle, particularly, relates to the controlling apparatus and method for controlling the duty ratio of the cooling fan associated motor of an engine cooling radiator and a condenser of a vehicular air conditioner.
b) Description of the Related Art
A Japanese Patent Application First Publication No. Heisei 11-229876 published on Aug. 24, 1999 exemplifies a previously proposed automotive vehicle cooling system having a cooling fan associated motor to cool a radiator and a condenser of a vehicular air conditioner through the cooling fans to cool a radiator of an engine and a condenser of the air conditioner.
A Pulse Width Modulation (PWM) is carried out by detecting a refrigerant pressure of the air conditioner and a coolant temperature and an air conditioner and calculating a duty ratio of the cooling fan in accordance with the coolant temperature and the refrigerant pressure.
However, since, in the above-described Japanese Patent Application Publication No. Heisei 11-229876, the duty ratio control for the motor is carried out with only the coolant temperature and a performance of the air conditioner taken into account, a fuel consumption of the whole vehicle often becomes worsened depending upon a situation of a motor operation.
In addition, since the cooling fan associated motor is constituted by two or more cooling fans and associated motors, a beat tone is often developed in accordance with individual product difference or fan profile difference when two or more motors are controlled at the same frequencies.
It is, hence, an object of the present invention to provide controlling apparatus and method for controlling a duty ratio of each cooling fan associated motor of an automotive vehicle.
According to one aspect of the present invention, there is provided a method for controlling a cooling fan associated motor at a pulse duty ratio, the cooling fan being revolved by the cooling fan associated motor to cool a radiator of a vehicular engine coolant and a condenser of a refrigerant of a vehicular air conditioner, the method comprising: controlling the duty ratio for the cooling fan associated motor in such a manner that a sum of a torque required for a generator to drive the cooling fan associated motor and a torque required to drive a compressor of the air conditioner is minimized while satisfying a control demand for a coolant temperature and a refrigerant pressure; and driving the cooling associated motor.
According to another aspect of the present invention, there is provided an apparatus for controlling a cooling fan associated motor at a pulse duty ratio, the cooling fan being revolved by the cooling fan associated motor to cool a radiator of a vehicular engine coolant and a condenser of a refrigerant of a vehicular air conditioner, the apparatus comprising: a controller to control the duty ratio for the cooling fan associated motor in such a manner that a sum of a torque required for a generator to drive the cooling fan associated motor and a torque required to drive a compressor of the air conditioner is minimized while satisfying a control demand for a coolant temperature and a refrigerant pressure; and a driver to drive the cooling associated motor at the duty ratio.
This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.